This invention relates to a loudspeaker apparatus and, more particularly, to a watertight loudspeaker apparatus which can be installed on a flat surface, e.g. a wall surface and a ceiling.
In general, loudspeaker apparatuses to be installed outdoors are exposed to rain and, therefore, they should be watertight. Conventionally, to make a loudspeaker apparatus watertight, it is enclosed with an airtight enclosure to seal off a vibrating plate of a driver from water, otherwise it would be exposed to external air and water. In order to permit adjustment of the direction in which sound is to be directed, a support device is attached to, for example, a wall of a building, and the loudspeaker apparatus is mounted with its enclosure supported by the support device in such a manner as to permit rotation of the enclosure about a vertical axis. In this case, however, the loudspeaker apparatus protrudes from the wall surface, which, undesirably, may not match the design of the building.
When loudspeaker apparatuses are installed on walls or the like, they may be frequently disposed at an upper location on the wall with the sound radiating aperture of the driver directed downward so that the radiated sound can propagate over a wide range. With the loudspeaker apparatus being tilted downward, sound radiated directly from the loudspeaker apparatus and sound reflected from the wall on which the loudspeaker apparatus is installed interfere with each other to produce peaks and dips of sound at frequencies. Peaks and dips occurring at lower frequencies give more unpleasant effects to auditory sense. Peaks and dips occur at lower frequencies as the distance of the center of the sound radiating aperture from the wall on which the loudspeaker apparatus is installed is larger. Accordingly, as the amount by which the loudspeaker apparatus protrudes from the wall is larger, adverse effects produced by peaks and dips are large, which may give unpleasant effects to auditory sense of audience.
According to another technique to make a loudspeaker apparatus watertight, the loudspeaker apparatus is fixed directly to an installation surface by, for example, screws, and the fixed portions are sealed with a watertight material, e.g. plastics so as to prevent water from penetrating through the fixed portions. With this technique, the amount of protrusion of the loudspeaker apparatus from the installation surface can be smaller, and, accordingly, the above-described peak-and-dip problem may be alleviated, but it is not easy to change the direction of sound emission once the loudspeaker apparatus has been fixed or to remove the loudspeaker apparatus for maintenance.
Therefore, an object of the present invention is to provide a watertight loudspeaker apparatus which can be installed on an installation surface with a relatively small amount of protrusion from the installation surface, can be installed and removed on and from the installation surface with ease, and can easily change the direction in which sound is radiated. Another object of the present invention is to provide a loudspeaker apparatus which can provide reduced effect of peaks and dips.
According to a first aspect of the present invention, a loudspeaker apparatus includes a disc-shaped installation device having one surface adapted to be fixed to an installation surface on which the loudspeaker apparatus is to be installed. The loudspeaker apparatus further includes a loudspeaker unit having at least one driver and an enclosure. The enclosure of the loudspeaker unit is disposed in such a manner that its rear surface abuts against the front surface of the disc-shaped installation device opposite to the installation surface. The loudspeaker unit radiates a sound wave over a propagation range extending about a sound radiation center axis which intersects, at a predetermined angle, the loudspeaker center axis of the loudspeaker unit extending perpendicularly to the rear surface of the enclosure. The loudspeaker apparatus further includes a coupling unit with which the loudspeaker unit can be mounted to the disc-shaped installation device in such a manner as to be detachable from the installation device and rotatable about the loudspeaker center axis.
The coupling unit may include a flange member formed around the outer periphery of the disc-shaped installation device, and engagement members attached to the outer periphery of the loudspeaker unit at a plurality of locations near the rear surface of the enclosure. The engagement members are detachably engageable with the flange member of the installation device, with the rear surface of the loudspeaker unit abutting against the front surface of the installation device.
A front portion of the installation device and a rear portion of the enclosure may be provided with generally annular portions which abut against each other or are closely spaced from each other. These annular portions are centered about the loudspeaker center axis so that the loudspeaker unit can be rotated about the loudspeaker center axis.
The installation device may be fixed to the installation surface with a first annular seal disposed between the installation device and the installation surface at a location radially inward of the flange member. In this case, the loudspeaker unit is mounted to the installation device with a second annular seal disposed between the loudspeaker unit and the flange member.
A dome-shaped mesh cover may be disposed to cover the front portions of the loudspeaker unit and the installation device.
According to a second aspect of the present invention, a loudspeaker apparatus includes a loudspeaker unit including an enclosure and a plurality of drivers. The loudspeaker unit has a loudspeaker center axis extending perpendicular to the rear surface of the enclosure, which is adapted to be brought into contact with an installation surface, e.g. a building wall, on which the loudspeaker apparatus is to be installed. The drivers are arranged substantially in a line, with their rear portions positioned near one surface of the loudspeaker apparatus, e.g. the rear surface of the enclosure. The drivers radiate respective sound waves over a range about their respective sound radiation center axes, which intersect the loudspeaker center axis of the loudspeaker unit at a predetermined acute angle in a plane which is perpendicular to the rear surface of the enclosure and contains the line along which the drivers are arranged.
The position of each of the drivers with respect to the above-mentioned one surface of the loudspeaker apparatus may be fixed.
The plurality of drivers may be spaced from one another by such a distance that the sound waves radiated from the respective drivers may not be interfered by one another""s exteriors.
Where drivers of different sizes are employed, a smaller-sized driver may be arranged on that side of a larger-sized driver toward which the sound wave center axis of the smaller-sized driver is tilted.
The loudspeaker apparatus may be a three-way loudspeaker apparatus which includes a woofer having a larger size, i.e. having a larger sound emerging aperture, a squawker having a smaller size, i.e. a smaller sound emerging aperture, than a woofer, and a tweeter having a size, i.e. a sound emerging aperture, smallest of the three. The squawker is disposed on the side of the woofer toward which the sound wave center axis of the woofer is tilted, and the tweeter is disposed on the side of squawker toward which the sound wave center axis is tilted.
The above-mentioned one surface of the loudspeaker apparatus may be arranged to orthogonally intersect a plane substantially parallel to a vertical plane containing a position where an audience is. The sound radiation axes of the drivers lie in a plane orthogonal to said one surface.